From aa5cb7f5e8bf2e6737d0cb36c118332ca26e7797 Mon Sep 17 00:00:00 2001 From: =?UTF-8?q?Marc-Andr=C3=A9=20Lureau?= Date: Mon, 4 Jul 2016 17:38:23 +0200 Subject: [PATCH] char: do not use atexit cleanup handler MIME-Version: 1.0 Content-Type: text/plain; charset=UTF-8 Content-Transfer-Encoding: 8bit It turns out qemu is calling exit() in various places from various threads without taking much care of resources state. The atexit() cleanup handlers cannot easily destroy resources that are in use (by the same thread or other). Since c1111a24a3, TCG arm guests run into the following abort() when running tests, the chardev mutex is locked during the write, so qemu_mutex_destroy() returns an error: #0 0x00007fffdbb806f5 in raise () at /lib64/libc.so.6 #1 0x00007fffdbb822fa in abort () at /lib64/libc.so.6 #2 0x00005555557616fe in error_exit (err=, msg=msg@entry=0x555555c38c30 <__func__.14622> "qemu_mutex_destroy") at /home/drjones/code/qemu/util/qemu-thread-posix.c:39 #3 0x0000555555b0be20 in qemu_mutex_destroy (mutex=mutex@entry=0x5555566aa0e0) at /home/drjones/code/qemu/util/qemu-thread-posix.c:57 #4 0x00005555558aab00 in qemu_chr_free_common (chr=0x5555566aa0e0) at /home/drjones/code/qemu/qemu-char.c:4029 #5 0x00005555558b05f9 in qemu_chr_delete (chr=) at /home/drjones/code/qemu/qemu-char.c:4038 #6 0x00005555558b05f9 in qemu_chr_delete (chr=) at /home/drjones/code/qemu/qemu-char.c:4044 #7 0x00005555558b062c in qemu_chr_cleanup () at /home/drjones/code/qemu/qemu-char.c:4557 #8 0x00007fffdbb851e8 in __run_exit_handlers () at /lib64/libc.so.6 #9 0x00007fffdbb85235 in () at /lib64/libc.so.6 #10 0x00005555558d1b39 in testdev_write (testdev=0x5555566aa0a0) at /home/drjones/code/qemu/backends/testdev.c:71 #11 0x00005555558d1b39 in testdev_write (chr=, buf=0x7fffc343fd9a "", len=0) at /home/drjones/code/qemu/backends/testdev.c:95 #12 0x00005555558adced in qemu_chr_fe_write (s=0x5555566aa0e0, buf=buf@entry=0x7fffc343fd98 "0q", len=len@entry=2) at /home/drjones/code/qemu/qemu-char.c:282 Instead of using a atexit() handler, only run the chardev cleanup as initially proposed at the end of main(), where there are less chances (hic) of conflicts or other races. Signed-off-by: Marc-André Lureau Reported-by: Andrew Jones Message-Id: <20160704153823.16879-1-marcandre.lureau@redhat.com> Signed-off-by: Paolo Bonzini --- include/sysemu/char.h | 7 +++++++ qemu-char.c | 4 +--- vl.c | 2 ++ 3 files changed, 10 insertions(+), 3 deletions(-) diff --git a/include/sysemu/char.h b/include/sysemu/char.h index 57df10aa00..0ea9eacc40 100644 --- a/include/sysemu/char.h +++ b/include/sysemu/char.h @@ -151,6 +151,13 @@ CharDriverState *qemu_chr_new(const char *label, const char *filename, */ void qemu_chr_disconnect(CharDriverState *chr); +/** + * @qemu_chr_cleanup: + * + * Delete all chardevs (when leaving qemu) + */ +void qemu_chr_cleanup(void); + /** * @qemu_chr_new_noreplay: * diff --git a/qemu-char.c b/qemu-char.c index 0698b98750..e4b8448422 100644 --- a/qemu-char.c +++ b/qemu-char.c @@ -4548,7 +4548,7 @@ void qmp_chardev_remove(const char *id, Error **errp) qemu_chr_delete(chr); } -static void qemu_chr_cleanup(void) +void qemu_chr_cleanup(void) { CharDriverState *chr, *tmp; @@ -4603,8 +4603,6 @@ static void register_types(void) * is specified */ qemu_add_machine_init_done_notifier(&muxes_realize_notify); - - atexit(qemu_chr_cleanup); } type_init(register_types); diff --git a/vl.c b/vl.c index cad4da2487..d3ec5320ea 100644 --- a/vl.c +++ b/vl.c @@ -4608,7 +4608,9 @@ int main(int argc, char **argv, char **envp) tpm_cleanup(); #endif + /* vhost-user must be cleaned up before chardevs. */ net_cleanup(); + qemu_chr_cleanup(); return 0; }